Clean remote url if necessary

Make sure that the remote URL does not contain a trailing slash.

Closes gh-4297

spring-boot-devtools/src/main/java/org/springframework/boot/devtools/RemoteUrlPropertyExtractor.java

@@ -46,7 +46,7 @@ class RemoteUrlPropertyExtractor
 	@Override
 	public void onApplicationEvent(ApplicationEnvironmentPreparedEvent event) {
 		ConfigurableEnvironment environment = event.getEnvironment();
-		String url = environment.getProperty(NON_OPTION_ARGS);
+		String url = cleanRemoteUrl(environment.getProperty(NON_OPTION_ARGS));
 		Assert.state(StringUtils.hasLength(url), "No remote URL specified");
 		Assert.state(url.indexOf(",") == -1, "Multiple URLs specified");
 		try {
@@ -60,6 +60,13 @@ class RemoteUrlPropertyExtractor
 		environment.getPropertySources().addLast(propertySource);
 	}
 
+	private String cleanRemoteUrl(String url) {
+		if (StringUtils.hasText(url) && url.endsWith("/")) {
+			return url.substring(0, url.length() - 1);
+		}
+		return url;
+	}
+
 	@Override
 	public int getOrder() {
 		return Ordered.HIGHEST_PRECEDENCE;

spring-boot-devtools/src/test/java/org/springframework/boot/devtools/RemoteUrlPropertyExtractorTests.java

@@ -79,6 +79,13 @@ public class RemoteUrlPropertyExtractorTests {
 				is(nullValue()));
 	}
 
+	@Test
+	public void cleanValidUrl() throws Exception {
+		ApplicationContext context = doTest("http://localhost:8080/");
+		assertThat(context.getEnvironment().getProperty("remoteUrl"),
+				equalTo("http://localhost:8080"));
+	}
+
 	private ApplicationContext doTest(String... args) {
 		SpringApplication application = new SpringApplication(Config.class);
 		application.setWebEnvironment(false);